The invention relates to an electrode with a net-like open pore system and with a ceramic and a metallic meshwork. The mesh works penetrate each other.
The invention also resides in a method of manufacturing such an electrode.
The open pore system facilitates a material transport through the electrode. The ceramic meshwork provides for the mechanical stability of the electrode. The metallic meshwork serves as electron conductor and as catalyst.
Such an electrode, that is, an anode of a high temperature fuel cell is disclosed in published German patent application No. 196 30 843.7. It has an open pore system, that is, it is porous throughout. Materials such as gaseous fuel, oxidation media or water may pass through the anode. The ceramic mesh work consists of zirconium oxide. It makes the electrode mechanically stable. The metallic meshwork consists of nickel. It conducts electrons and serves as a catalyst for the chemical reactions, which take place in the high temperature fuel cell.
It is however disadvantageous that there is a self-diffusion of the metal. Under high temperature conditions, a diffusion of metal in metal takes place in the anode, that is, for example nickel diffuses in nickel or platinum in platinum. The self-diffusion results in a coagulation that is in an increase of the metallic mesh work. The increased reduces the electrochemically active surface area. The electrochemically active surface area is the surface on which the electrochemical reactions take place which are necessary for the operation of the fuel cells. When the electrochemically active surface area of the fuel cell becomes smaller, the capacity of the fuel cell becomes smaller.
It is the object of the present invention to provide an electrode, which is efficient and effective over a long period of time.